1. Field of the Invention
The present invention relates to an angle measuring instrument and to a method for producing the angle measuring instrument.
2. Discussion of Related Art
One such angle measuring instrument includes a flexible (in particular, flexibly elastic, longitudinally rigid) band, for instance in the form of a steel band, which as a graduation support has a measuring graduation that can be scanned (for instance magnetically or optically) by a suitable scanner unit, and also includes an annular support body, that is, one that forms a ring or an annular portion surrounding a longitudinal axis and on which the graduation support is fixed extending annularly all the way around, or in other words again forming a ring or an annular portion. The measuring graduation is mounted on the outside of the flexible band in such a way that the measuring graduation extends in the circumferential direction on the outer wall of the annular arrangement formed by the support body and the graduation support.
From German Patent Disclosure DE 199 56 833 A1, it is known to fasten a tensible tape measure, by a chuck that has a turnbuckle, to the outer circumference of a circular table; the two free ends of the tape measure, connected to one another via the turnbuckle, are placed in an abutting relationship in such a way that across the abutment, precisely one graduation period results. Note that German Patent Disclosure DE 199 56 833 A1 corresponds to U.S. Pat. No. 6,523,268, the entire contents of which are incorporated herein by reference.
From European Patent Disclosure EP 0 874 996 B1, an angle measuring instrument is known in which a graduation support in the form of a plastic ring has a measuring graduation formed by magnet poles, and together with it is fixed by a cage ring on the outer wall of an annular support body in the form of a base ring. The measuring graduation disposed on the outer wall of the base ring by the plastic ring and cage ring can be scanned with a scanner unit, which scans the outer surface of the rotatable annular arrangement formed by the base ring, plastic ring, and cage ring. Note that European Patent Disclosure EP 0 874 996 B1 corresponds to U.S. Pat. No. 6,087,748, the entire contents of which are incorporated herein by reference.
In German Utility Model DE 87 17 505 U1, an angle measuring instrument is described in which a pulse ring is disposed on the outer jacket face of the outer ring of a wheel bearing. The pulse ring is secured to the outer jacket face of the outer ring by welding the two free ends of a band, forming the pulse ring and bent into a ring, to one another and pressing the pulse ring onto the outer ring.
For high-precision angle measuring systems, the fixation of a flexible tape measure on an annular body or a circular table, as described in DE 199 56 833 A1, has proved especially advantageous. However, the problem exists that the increased space requirement because of the turnbuckle is disadvantageous in certain applications, especially in small angle measuring systems. Furthermore, the imbalance represented by the turnbuckle, upon a rotary motion of the support of the measuring graduation at high rpm, can lead to high bearing stress and hence a short bearing life. Moreover, a permanent imbalance causes eccentricities that in turn generate a measurement error.
Joining the ends of a tape measure by welding, if the base body has small diameters, leads to correspondingly major bending stresses at the weld seam, which impair its strength. Moreover, the use of a welding method in creating a high-precision position measuring system is hindered by the problem that the heat development occurring during welding can change the length of the graduation periods in the region of the band ends to be welded.